This invention is in the fields of organic chemistry, and relates to compounds that inhibit the formation of nitrosamines that may be carcinogenic, by scavenging and reacting with nitrosating agents.
Background information on nitrosamine and N-nitroso compounds is contained in the specification of the above-cited parent application, the contents of which are hereby incorporated into this application by reference. For convenience, the term "nitrosamine" is used herein to include N-nitroso compounds, since the risks they pose and the methods of removing them from unwanted locations are similar.
Briefly, nitrosamines (and N-nitroso compounds) can be generated when nitrosating agents (such as nitrous acid, NO.sub.X, and various nitrous esters, metal nitrites, and nitrosyl or nitro compounds) react with other molecules containing amine groups. The resulting nitrosamines are present as undesired byproducts or contaminants in certain foods and in various liquids that contact skin, including cosmetics, hygiene products such as shampoos, fluids used during various machining or manufacturing processes, hydraulic fluids, pesticides, and other commercial chemicals. They can also be released into the air during certain manufacturing processes such as rubber molding. These exposures pose a health risk, since many nitrosamine and nitroso compounds have been shown to be carcinogenic in tests using laboratory animals. In general, all nitrosamines are presumed to be carcinogenic unless they've been tested and shown to be relatively harmless.
The co-pending parent application cited above disclosed a method of coupling certain types of reactive side groups to organic polymeric backbones. In one preferred embodiment of that invention, the reactive side groups are immobilized on the surfaces of polymeric particles. The immobilized side groups react with nitrosating agents in a liquid which is being treated, in a manner which converts the nitrosating agents into residues that are immobilized on the particles. The particles can then be removed from the liquid by means such as filtering, thereby removing the nitrosating agent and reducing nitrosamine formation in the liquid.
The invention disclosed herein extends that invention by using the same reactive side groups coupled to inorganic substrates, such as glass beads, silica, metal or metal-containing compounds (which can contain ferromagnetic elements such as iron), and ceramic compounds. Extending the range of substrates into the realm of inorganic substances such as glass and metal provides various advantages such as greater rigidity, hardness, temperature stability, potentially lower cost of manufacture, better control of particle size, and the ability to treat liquids which might dissolve, degrade, react with, or otherwise interact in an adverse manner with organic polymers. It also provides additional options for particle removal, such as magnetic attraction if ferromagnetic particles are used, and it allows a wider range of non-particulate substrate configurations, such as stirring paddles, baffles, or fibrous strands having any desired dimensions.
Accordingly, one object of this invention is to disclose that various inorganic substances such as controlled-pore glass, silica, ceramics, or ferromagnetic particles or devices can be used as substrates for immobilizing reactive groups which can inactivate nitrosating agents. Another object is to extend the range of liquids, reaction conditions, separation techniques, and other parameters that are involved when immobilized reactive groups are used to inactivate or remove nitrosating agents and reduce the formation of nitrosamines.